Electron discharge device



July 18, 1939. H. R. SEELEN ET AL ELECTRON DISCHARGE DEVICE Filed May 28, 1938 INVENTORS HARRY R. SEELENAND BY KEN/V57 M. MtlAl/i/ll/N wwa zw A TTORNEY.

Patented July 18, i939 UNITED STATES PATENT OFFICE ELECTRON DISCHARGE DEVICE Delaware Application May as, loss, Serial No. 210,648

4 Claims.

Our invention relates to electron discharge devices, particularly to electrode assemblies for such devices.

The electrodes of an electron discharge device are usually concentric cylinders with side rods or ears extending beyond the ends of the cylinders to engage holes in insulating spacers at the ends of the assembly. It is diflicult to telescope small electrodes and thread their extensions in the holes without damage to the parts, especially when the inter-electrode spacing and the holes are small. Further, the electrical characteristics of the conventional tube cannot be changed in manufacture without changing the size and shape of many of the parts in the electrode assembly.

An object of our invention is an electron discharge device with electrodes which are easy to assemble, rugged in construction, and inex- 2o pensive to manufacture.

Another object of our invention is an electrode assembly which may be easily made with parts that are interchangeable in a number oftubes of different electrical characteristics.

An electrode assembly constructed according to our invention comprises a plurality of planar type electrodes held in parallel spaced relation with vertical sheet-like insulating spacers adjacent the side edges and normal to the plane of the electrodes. Extensions such as ears or lugs on the side edges of the electrodes rest against steps or notches in the edges of the spacers in such a way that the length of the risers between the treads of the steps, on which the extensions bear, fixes the distances between the electrodes. Changes in electrode spacing may be made in. manufacture, with corresponding changes in electrical characteristics, by merely changing the configuration of the stepped edges of the spacers. 40 The characteristic features of our invention are defined with particularity in the appended claims and preferred embodiments are described in the following specification and shown in the accompanying drawing in which Figure 1 is a perspective view of an electrode assembly of our invention, Figure 2 is a detailed expanded view of electrodes constructed according to our invention; Figure 3 is an elevation of a shielded mount of our invention, Figure 4 is a detailed view of a shield which may be used in our improved tube, and Figure 5 is a detailed view of one cathode which may be used in our improved mount.

An electron discharge device with an electrode assembly constructed according to our invention 0 comprises an envelope I closed at its lower end with a stem or header 2 in which is scaled a plurality of lead-in conductors 3 joined at their upper ends to the electrodes of our novel electrode assembly. The electrode assembly chosen for illustrating our invention comprises a cathode 4, control grid 5, screen grid 6, suppressor grid I, and anode 8. The cathode, Figure 2, may conveniently comprise two grooved strips of refractory metal jointed along their edges to form a hollow sleeve in which an insulated heating element may be inserted. The strips of metal are blanked out with two pairs of parallel ears or lugs 9 which engage at their ends holes in the central portion of the two insulated spacers l0.

Each of the grid electrodes 5, 6 and I is a rectangular frame with parallel grid wires welded at their ends to the side members of the frame, which like the cathode are provided with two pairs of outwardly extending ears or lugs II on the side edges of the frame. The anode is a rectangular flat sheet of metal with the same outside dimensions as the frames of the grids and is provided with two pairs of outwardly extending ears or lugs II.

The insulating spacers. III of our improved mount are flat sheets of insulating material such as mica and as shown in Figure 1 are provided with a plurality of steps IS, the steps extending diagonally across the corners of the spacer.

When assembled the ear or lug extensions of the electrodes bear against thetread ll of the steps and the spacing between the electrodes is determined by the length of the risers l5, Figure 5, between the tread. The ears on each electrode may conveniently be elongated and registering ears joined as by spot welding at I at their ends along the vertical center line of the spacer.

Our improved electrodes are particularly easy to assemble. As distinguished from the conventional mount where electrodes are telescoped together and side rods are threaded through small openings, the planar type electrodes of our asheader with its upper ends joined to the strap ll encircling the mount. The shell is then joined to the stem, and the envelope exhamted and based in the usual manner.

The anode of our improved electrode mount v is easily shielded from the other electrodes in the tube. The electrostatic shielding of the screen grid may be extended to the walls or the envelope with thin metal plates it, Figure 4, Joined to or formed integrally with the ends of the screen grid frames, as shown in Figure 3. The shields are semi-circular and are bent normal to the plane of the screen grid to bring the curved edges oi the shields close to or into contact with the inner surface of the envelope. The shields may serve to center the electrode assembly within the envelope, and the depending ears 2! on the shields joined at their ends to the ends I of the screen grid ears, completely isolate the anode from the other electrodes.

In Figure 5 an alternative means ior supporting the cathode in the mount isshown. The sleeve of the cathode l, which may be exteriorly coated with electrode emissive oxides and which carries internally an insulated heating element, is Joined at its ends to wire-like spring fingers 2| curved outwardly and hooked into holes in the spacers. It will be obvious to those skilled in the art that many forms ofcathodes and means 01' mounting the cathodes may be employed in the manufacture of our improved electrode assembly without departing from the scope of our invention.

Electrodes assembled according to our invention may be stacked between the spacers by automatic machinery and thus obviate the tedious and costly hand work necessary in threading the usual side'rods through small spacer holes. Our improved electrode assembly is adapted to economical manufacturing technic where many tubes, although similar in constructon must have diilerent electrical characteristics. Some tubes, for example, diiier only in the spacing between electrodes. When constructed according to our invention these diflerent types of tubes may be made merely by selecting insulating spacers with the proper step configuration.

Our improved electrode assembly is particularly adapted for beam forming. The parallel cording to our invention is easy to assemble, is rugged in construction and inexpensive to manui'acture.

We claim:

1. An electron discharge device comprising a plurality of parallel planar type electrodes, each electrode being rectangular and having two ears extending from each of the side edges of the electrode, two flat spacers of insulating material normal to the plane and adjacent the side edges of the electrodes, steps along the edges of the spacers with the ears or the electrodes bearing against said steps for holding the electrodes in insulated spaced relation.

2. An electrode assembly comprising a plurality of parallel planar electrodes, each electrode being rectangular and having ear extensions on each of its side edges, two elongated flat insulating spacers against said side edges and normal to the plane of the electrodes, the width each elongated spacer being diiterent at its center from its ends, the edges 01' the spacers being stepped, means for holding the said extensions against said steps, the length of the risers between the treads of said steps being substantially equal to the spacing between adjacent electrodes.

3. An electrode assembly comprising a plurality of planar electrodes held in parallel spaced relation, two vertical sheet like insulating spacers adjacent the side edges of said electrodes and normal to the plane of the electrodes, ear extensions on the side edges of the electrodes resting against edges of the spacers, the point of contact between said edges and extensions of the different electrodes being successively stepped inwardly toward the center line of the spacers, the length of the risers between the treads of the steps being substantially equal to the distances between the electrodes. 1

4. An electrode assembly comprising a grid with a rectangular metal frame having end and side members, parallel wires joined at their ends to said side members, a rectangular metal plate or substantially the same dimensions as said grid, ears on the side edges of said plate and on said side members, the ears on the plate and on the grid being spaced diflerent distances from the ends of the electrodes, two spaced parallel insulating spacers normal to the plane of said electrodes, stepped, means for holding the plate ears and the grid ears against adjacent steps, and a cathode supported on said spacers in cooperative relation with the grid and plate.

HARRY R. SEELEN. KENNETH M. MCLAUGHLIN.

the edges 01' said spacers being. 

